EFEECT OF INCREASING PROTEIN LEVEL FROM FISHMEAL AND SWEET POTATO LEAF MEAL IN DIET ON PERFORMANCE OF GROWING PIGS UNDER VILLAGE CONDITIONS IN CENTRAL VIETNAM

Nguyen Thi Hoa Ly, Nguyen Thi Loc, Du Thanh Hang and Truong Thi Thuan

Hue University of Agriculture and Forestry
Hue City, Vietnam
lydohoai@dng.vnn.vn

Abstract

The present study aimed at evaluating the effect of increasing the protein level in the diet, supplied by fish meal and sweet potato leaf meal, on the performance of growing pigs. The sweet potato leaf meal used had a crude protein (CP) content of 16.5 % (DM basis). Three farmers kept twenty - four crossbred pigs (MC x LW) with an average initial live weight of 19.4 kg that were randomly allocated into 4 treatment groups, with 4 pens and two pigs per pen on each farm. The four experimental diets were formulated according to the two growing phases, 20 to 50 kg (phase 1) and 50 to 90 kg (phase 2), and contained (% of DM): Low, 12 and 10 % CP; Medium, 14 and 12 % CP; High, 16 and 14 % CP; and Very high, 18 and 16 % CP in phase 1 and phase 2, respectively. The protein supplement consisted of a mixture of 30 % fishmeal and 70 % sweet potato leaf meal (as DM) and replaced a mixture of rice bran and ensiled cassava roots.

There were no treatment effects on final live weight, daily live weight gain and feed conversion ratio, but the cost of feed per kg live weight gain was significantly higher for the very high protein level, because of the high cost of fish meal.

Dietary protein levels of 14 % CP for pigs of 20 to 50 kg and 12 % CP for pigs of 50 to 90 kg (as DM) with the protein supplied by fishmeal and sweet potato leaf meal can be recommended as they resulted in reasonably good growth performance and gave the best economical efficiency. Sweet potato based pig production systems play an important role in the economies of small farmers in Central Vietnam.

Key words: Conversion, growth, pigs, protein, sweet potato leaves

Introduction

Protein plays an important role in pig nutrition and a considerable amount of work has been done on the effect of different protein levels in the diet on the growth performance of pigs (Heucken 1963; Jarop and Lopax 1972; Hale and Chley 1986; Ocampo et el 1990; Le Dinh Phung 1999; Nguyen Kim Duong and Le Dinh Phung 2000; Hoang Nguyen Duyet 2000).

The main protein sources in pig diets in Central Vietnam are fish meal, soybean meal, groundnut cake and shrimp by-products, but they are relatively expensive and not available in remote villages. Thus, it is very important to identify local sources of protein, especially those that can be produced on small farms. In Vietnam, sweet potato (Ipomoea batatas L. (lam)) is the third most commonly grown crop after rice and maize and occupied 296,000 ha in 1999 (Statistical Yearbook 2000). Sweet potato is usually the main food crop in areas where rice production is limited, but at present it is more commonly used for livestock: both tubers and vines are use for pigs, chickens and cattle. It has potential for development at the poor farm level as it can be planted and harvested all year around. Sweet potato leaf meal has a high protein content of 17 to 20 % in DM (Anon 1995; Le Van An 2001) and thus can be used as a protein supplement for pigs. Sweet potato based pig production systems are very common in Central Vietnam and play an important role in the economies of small farmers.

The present study aimed at evaluating the effect of different protein levels in diets for growing-fattening pigs on growth performance, with the protein supplied by a mixture of fishmeal and sweet potato leaf meal. The ultimate aim was to improve the well-being of the poor small-scale farmers in Central Vietnam.

Materials and methods

Location

The experiment was carried out in three households in Huong van village, Huong tra District, Thua Thien Hue province from January 2001 to May 2002.

Animals, experimental design and feeding

Three farmers were selected to carry out the on-farm experiment, and raised a total of 24 crossbred (Mong Cai x Large White) pigs with average initial live weight of 19.4 kg. Each farmer was allocated 8 pigs randomly distributed into four treatments (pens), with two pigs in each pen. The pigs were vaccinated against hog cholera and Pasteurellosis, and de-wormed 2 weeks before starting the experiment. The diets were formulated according to the two growing phases, 20to 50 kg (phase 1) and 50 to 90 kg (phase 2). The diets were fed according to a restricted allowance recommended by the National Institute of Animal Husbandry (1995). The experiment lasted 90 days. The daily feed allowance was distributed equally into 3 meals per day. Refusals were collected the following morning before the first meal. Drinking water was available ad libitum.

The four dietary treatments in phase 1 and phase 2, respectively, were:

Low, 12 and 10 % CP;

Medium, 14 and 12 % CP;

High 16 and 14 % CP;

Very high, 18 and 16 % CP,

The protein supplement was a mixture of 30 % fishmeal and 70 % (as DM) sweet potato leaf meal (Table 1).

Table 1. Chemical composition of the feed ingredients
Ingredient	DM (%)	ME* (kcal/kg DM)	CP in DM (%)	Fat in DM (%)	CF in DM (%)
Rice bran	89.3	2855	11.2	7.6	14.9
Yellow maize	85.2	3691	9.80	4.3	2.10
Ensiled cassava root	40.6	2958	3.03	1.73	3.97
Sweet potato leaf meal	91.2	2522	16.5	5.70	21.0
Fish meal	90.2	3416	58.3	6.77	-
* Calculated

Table 2. Ingredient and chemical composition of the diets in Phase 1 (20 - 50 kg)

Low

Medium

High

Very high

Rice bran

Yellow maize

Ensiled cassava root

Sweet potato leaf meal

Fish meal

Min and vitamin premix

NaCl

Composition, ( %)

ME (kcal/kg DM)

Crude protein in DM

Crude fibre in DM

10.5

4.5

0.5

3043

12.0

9.77

16.8

7.2

0.5

3032

14.0

10.2

3.1

22.5

9.4

0.5

3017

16.0

11.1

0.5

2980

17.6

11.6

Table 3. Ingredient and chemical composition of the diets in Phase 2 (50 to 90 kg)

Low

Medium

High

Very high

Rice bran

Yellow maize

Ensiled cassava root

Sweet potato leaf meal

Fish meal

Min and vitamin premix

NaCl

Composition ( %)

ME (kcal/kg DM)

Crude protein in DM

Crude fibre in DM

0.5

2992

10.1

10.0

10.5

4.5

0.5

3043

12.0

9.77

16.8

7.2

0.5

3032

14.0

10.2

3.1

22.5

9.4

0.5

3017

16.0

11.1

Measurements

Feed consumption was determined by weighing the amounts given and subtracting any feed remaining the following morning. The pigs were individually weighed initially, monthly and at slaughter, and daily weight gain, daily feed intake, feed conversion ratio and feed cost / kg live weight gain calculated for each treatment.

The data were analyzed by the General Linear Model (GLM) procedure in the ANOVA program of Minitab Software. Sources of variation were: treatments and error.

Results and discussion

Final live weight, daily weight gain and feed conversion ratio

Final live weight and daily weight gain tended to increase as level of protein in the diets increased to the "high" level, an then decreased at the "very high" level (Table 4). The pattern for feed conversion was similar.

Table 4. Effect of protein level in the diet on the growth and economic performance of crossbred growing pigs
	Low	Medium	High	Very high	SEM	Prob.
Live weight, kg
Initial Final Daily gain Feed data DM intake, kg /day DM conversion Feed cost *	19.7 67.8 0.535 1.50 2.91 6693^a	19.2 69.6 0.560 1.57 2.80 6278^b	19.5 74.2 0.608 1.59 2.63 6887^a	19.1 70.9 0.576 1.57 2.73 7397^a	0.68 2.32 0.024 0.038 0.093 243	0.918 0.293 0.217 0.951 0.213 0.030
* VND/ kg live weight gain; ^abMeans with different superscripts within rows are different at P<0.05

Feed costs

The feed costs / kg gain for the medium protein treatment (14 -12 % CP) were lower (P<0.05) than for the Very high protein level, which was highest due to the high cost of fishmeal.

Diets with 14 and 12 % CP in the growing and finishing phases, respectively, thus gave the highest economical efficiency and can be recommended for F1 (MC x LW) fattening pigs. Similar findings were reported by Le Dinh Phung (1999), Nguyen Kim Duong and Le Dinh Phung (2000), who also concluded that increasing the crude protein level in diets from 12 to 17 % resulted in higher feed expenditure, but did not have a significant effect on meat quality in the carcass.

Conclusions

· Dietary levels of 14 % and 12 % CP (as DM) can be recommended for crossbred pigs of 20 to 50 kg and 50 to 90 kg, respectively.

· A mixture of sweet potato leaf meal and fish meal can be used as a protein supplement for feeding pigs under village conditions.

References

Anon 2000 General Statistics Office. Statistics Publishing House

Crampton E W and Harris L E 1969. Applied Animal Nutrition. Printed by W.H.Freeman

and company, pp 49.

Le Duc Ngoan 2000 Evaluation of shrimp by-products for pigs in Central Vietnam. Doctoral Thesis. Swedish University Of Agricultural Sciences. Uppsala

Le Dinh Phung 1999 Effect of different protein level in diets on productivity and carcass quality of F1 hybrid ( MC x LW) fattening pigs. MSc. Thesis. Hue University

Nguyen Kim Duong and Le Dinh Phung 2000 Effect of different protein levels in diets on productivity and carcass quality of F1 hybrid ( MC x LW) fattening pigs. Hue University of Agricultural and Forestry, Results of Researches on Technologies and Sciences of Agriculture, Forestry. Agricultural Publishing House, Hanoi

NRC 1998 Nutrient requirements of swine. Tenth Revised Edition, National Research Council

Peters D and et al 2001 Pig feed Improvement through Enhanced Use of Sweet Potato Roots Vines in Northern and central Vietnam. International Potato center ( CIP)

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Effect of dietary protein level on the performance of growing pigs under village conditions in Central Vietnam